Diaphragm



Patented Jan. 21, 1930 UNI-TED STATES NATHANIEL BALDWIN,A OF EAST MILL CREEK, UTAE DIAIHBAGM n Application led August 8, 1924. Serial No. 730,914. I

The present invention appertains td diaphragms for acoustic purposes, such as for phonograph recorders, phonograph yrepro-`V with diaphragms, thus producing increasedVv J0, efficiency as a sound producer or as a converter of sound Waves into mechanical energy.

In this invention the object is attained by making the central or main part of the diaphragm cone-shaped, dished. or otherwise 1.; curved to stili'en it and to provide for the necessary flexibility at or near the edge of the diaphragm by means of a zone which is plane, corrugated, or formed With over-lapping folds.

The invention is illustrated inthe accompanying drawing in Which- Fig. 1 is a vertical cross section of the diaphragm in its simplest form. Fig. 2 is a vertical cross-se'ction of a modification of the diaphragm shown in Fig. l. Fig. 3 is a vertical cross-section of a modification of the diaphragm shown in Fig. 2. Figs. 4 :and 5 are vertical cross-sections of modifications of the diaphragm shown in Fig. 3. In the several figures the central annular portion AB is cone-shaped, dished, or other,- wise curved which renders it rigid, While the concentric annular portion BC is flat, or corrugated in such way as to render it more flexible. The concentric annular portion or edge CD is adapted to be clamped upon the diaphragm seat in Whatever instrument the de v1ce is used.

The flexible portion BC of the diaphragm shown in Fig. l is fiat; in Fig. 2 it is corrugated; in Fig. 3 it is formed into an overlapping fold; in Figs. 4 it is formed into an overlapping fold on one side of the diaphragm; and in Fig. 5 it is formed into several over-lapping folds presenting theform of a bellows.

In either of the forms illustrated a vibratory force applied at the center will cause the portion AB lto vibrate as a Whole, while the portion BC yields to the movement. The re sult is increased efficiency as a sound producer over the ordinary flat or corrugated diaphragm which is flexible throughout and responds to the full movement only at the center. Therefore, either of the forms of diarphragms here illustrated Will have increased efficiency when used in a phonograph reproducer, in a telephone receiver, in a loud speaker, etc.

If the central portion of either of the diaphragms here illustrated is operatively connected to any other mechanism,- and sound Waves beat upon the diaphragm, the effect of the sound upon the entire surface AB will be concentrated at the point of connection becausethis portion AB is rigid, whilein the case of the ordinary flat or corrugated diaphragm the larger portion of the force of the sound Waves is impressed upon the diaphragm seat. Therefore, either of the forms of diaphragme here illustrated will have increased eliiciency when used in a phonograph recorder, microphone, etc.

` I claim: I

1. A diaphragm having a relatively rigid central zone, a substantially plane peripheral' edge zone, and a folded zone adjacent the periphery, said folds having such shape that portions of said folded 'zone other than crest portions thereof are substantially parallel to the peripheral portion.

-2. A diaphragm having a relativelyrigud central portion, a peripheral portion, and a recumbent fold formed adjacent said peripheral portion.

3. A diaphragm having a relatively rigid non-plane central zone, a substantially plane peripheral edge portion, and a relatively ilexible portion adjacent the periphery, said ilexible portion having crenulations whereof parts other than the crests lie substantially parallel to the plane peripheral portion.

NATHANIEL BALDWIN. 

